Methyl 2-hydroxyethyl methyl (methylol) phosphinates and process for their production

ABSTRACT

Novel compounds of the present invention represented by the following structural formula. WHEREIN R is methyl or hydroxymethyl. The process for their preparation is also included. The novel compounds of the present invention are useful in imparting flame retardancy to fibrous materials.

United States Patent 1 1 Shields 1451 Jan. 16, 1973 22 Filed;

[ METHYL Z-HYDROXYETHYL METHYL (METHYLOL) PHOSPHINATES AND PROCESS FORTHEIR PRODUCTlON [75] Inventor: Theodore Curtis Charleston, W. Va.

Shields, South [73] Assignee: Union Carbide Corporation, New

York,N.Y.

21 Appl. No.: 85,774

UNITED STATES PCATENTS 3,005,020 10/1961 Buckler ..200/9s3x PrimaryExaminer- Lewis Gotts Assistant Examiner-Anton H. Sutto Att0rneyPaul A.Rose, Aldo John Cozzi and Clement .1. Vicari [57] ABSTRACT Novelcompounds of the present invention represented by the followingstructural formula.

wherein R is methyl or hydroxymethyl. The process for their preparationis also included. The novel compounds of the present invention areuseful in imparting flame retardancy to fibrous materials.

8 ClaimsQNo Drawings METHYL Z-HYDROXYETHYL METHYL (METHYLOL)PHOSPHINATES AND PROCESS FOR THEIR PRODUCTION This invention relates tonovel phosphorus containing compounds. More particularly the inventionrelates to the novel compounds, i.e., methyl2-hydroxyethylmethylphosphinate and methyl2-hydroxyethylmethylolphosphinate and to the process for theirproduction.

The novel compounds of the present invention may be represented by thefollowing structural formula.

9 CHaOllCHzCHrOH wherein R is methyl or hydroxymethyl. The novelcompounds are useful in imparting flame retardancy to a wide host offibrous materials.

In general, the novel compounds of the present invention may be producedby reacting elemental phosphorus with an alcohol, preferably methanol,and ethylene oxide in the presence of a basic catalyst, preferablyN,N-dimethylethanolamine to produce thereby an organophosphoruscomposition. This portion of the process is carried out by contactingthe reactants in a suitable reaction vessel. The order of addition isnot critical. The reaction temperature can vary widely, for instance,elevated temperatures of from about 25C. to about 200C. are suitable,and temperatures of from about 44C. (the melting point of phosphorus) toabout 150C. are preferred. The reaction is carried out for a period oftime sufficient to produce an organophosphorus composition. Forinstance, reaction times of from about 10 minutes to about 10 hours aresuitable, depending upon temperature and the like. If desired, an inertorganic diluent can be employed for the reaction. Suitable diluentsinclude toluene, methyl isobutyl ketone, dioxane, dimethyl-sulfoxide,and the like. It is usually desirable to blanket the reaction mixturewith an inert atmosphere such as nitrogen. The organophosphoruscompositions produced thereby are thereafter reacted with an aldehyde,preferably formaldehyde, in order to convert substantially all of thephosphinous hydrogen (i.e., hydrogen bonded directly to phosphorus) tohydroxymethyl. The formaldehyde addition reaction is carried out simplyby adding the formaldehyde to the organophosphorus compositions andcontacting until substantially all of the phosphinous hydrogen has beenconverted to hydroxymethyl groups in accordance with the reaction:

wherein R represents hydrogen or an aliphatic or aromatic group.

This reaction, which is usually exothermic, will take place at roomtemperature, although higher or lower temperatures can be employed ifdesired. At room temperature, the aldehyde addition reaction usuallytakes place from about 0.1 to 6 hours, after which the product can berecovered by vacuum evaporation of excess aldehyde. The aldehyde ispreferably employed in proportions slightly in excess of the amountneeded to react with all of the phosphinous hydrogen.

The above procedure is described in detail in the application of ChisungWu, Ser. No. 886,037 filed Dec. 17, 1969 now US. Pat. No. 3,644,595 andassigned to a common assignee and is incorporated herein by reference.

To the reaction product produced according to the above describedprocedure there is added an amount of a solvent such as methanol,ethanol or ethylene glycol (hereinafter called primary solvent) theaddition being accompanied by agitation and the quantity, beingsufficient to enhance the fluidity of the reaction products resultingfrom the above described procedure. This step is followed by addition ofanother, less-polar solvent such as diethyl ether, dioxane, diglyme,glyme, and the like resulting in precipitation of an insoluble, highermolecular weight material. The proportions of solvents may be varied atwill. With increasing amounts of primary solvent in the first stepdecreasing precipitation of high molecular. weight materials occurs;with increasing amounts on non-polar cosolvents increasing precipitationoccurs.

As a general rule, there can be employed in the first step an amount ofprimary solvent within therange of 5 to 30 parts per hundred parts ofphosphorus reaction product by weight. The amount of solvent in thefirst step to the amount employed in the second can vary from about 7 to15 parts by weight co-solvent to primary solvent by weight. An optimumprocedure involves addition of sixty ml. dry methanol to g. of colorlessviscous liquid followed by addition of about 400 ml. diethyl ether.There are generally two phases which form an upper phase and a lowerphase. The upper phase is separated and the solvent removed by vacuum ata temperature below about 60C. Other techniques for removing the solventare well known in the art and hence no detailed description ofprocedures is deemed necessary. The residue, i.e., the product remainingafter solvent removal is thereafter introduced into a vessel, equippedwith agitating means, reflux-condenser, and entry ports for theintroduction of nitrogen. To the vessel there is also introduced acompound such as N,O-bis-trimethylsilylacetamide,trimethylsilylimidazole and 'N,O-bis-trimethylsilyltriflouroacetamide,which compound is normally added over a period of from about 2 to 60minutes. Nitrogen is continually introduced to the medium. The medium isagitated for about 2 to 30 minutes. i

The product material, i.e., the trimethylsilylated derivatives of thenovel compounds may then be vacuum flash distilled to separate it fromacetamide and residue tars if desired. Separation of thetrimethylsilylated derivatives of the novel compounds can thereafter beaccomplished by preparative vapor-liquid chromatography on a boilingpoint column such as silicone gum rubber at column temperatures betweenabout 60C. and 250C. Precautions must be taken to exclude moisture fromthe exit port, if the trimethylsilylated derivatives are to remainunhydrolyzed. If the novel compounds themselves are desired it isconvenient to permit hydrolysis in air since spontaneous hydrolysis atthe exit port results in transformation to the original phosphorousalcohols contained in the product mixture. The alcohols are collected incold traps while trimethylsilanol, the other hydrolysate frac tion,escapes as a volatile gas.

As mentioned previously the novel compounds of the present inventionhave utility as flame retardants for a wide variety of fibrousmaterials. The treatment to impart flame retardancy to fibrous materialmay be applied to any fibrous material containing primarily cellulosicfibers such as cotton, viscose rayon, cellulose rayon, or to mixtures ofvarious fibers with cotton such as cotton polyester fibers,cotton/synthetic fibers, cotton/wool fibers, and the like. Productswhich can be flame retarded and which are fabricated from the abovefibers include synthetic wool coverings; textile fabric wall coverings;lamp shades; automobile upholstery; upholstery for furniture; clothing;apparel accessories, for example, ties, fabric belts, scarfs, etc.draperies; throw pillows; fabric garment bags and luggage; mattresscovers and the like.

The following examples will illustrate the present invention. In theexamples all temperatures are in degrees centigrade unless otherwiseindicated.

EXAMPLE 1 31 g. of yellow phosphorous, 27 g. of methanol, 36 g. ofethylene oxide and 9 g. of N,N-

dimethylethanolamine were admixed and allowed to react over a minuteperiod at 88C. to produce a red molten mixture. To the resulting redmolten mixture was added dropwise a mixture of 11 g. of ethylene oxideand 7.0 g. of methanol and to the resulting mixture was added 28 g. offormaldehyde as a 55 percent solution in water and methanol. Evaporationof the reaction mixture to constant weights yielded a light yellow,water-insoluble, viscous liquid containing 21% P.

EXAMPLE 2 201 g. of a colorless viscous liquid produced as in Examplewas introduced into a mechanically stirred 2 liter, three-necked,round-bottom Pyrex flask containing 120 ml. dry methanol and equippedwith nitrogen purge. After the stirred mixture became one phase 800 ml.diethyl ether was introduced slowly over a period of 30 minutes at 25C.The material became turbid and finally separated into two translucentlayers. The upper (ether) phase was transparent after standingovernight. Separation of the upper phase followed by removal of etherunder partial vacuum at 60 afforded 12.4 g. of material (etherfraction).

The ether fraction was stirred mechanically in a 250 ml., round-bottom,three necked Pyrex flask equipped with nitrogen purge andreflux-condenser. N,O-bistrimethylsilylacetamide (14.58 g.) was addedover a period of 15 minutes with stirring. After stirring an additional120 minutes the mixture was one phase.

Vacuum fractional distillation afforded, in addition to acetamide andN,O-bis-trimethylacetamide, four product cuts: (1) 4.18 g. at 56/0.70mm, (2) 10.65 g. at 68/0.17 mm, (3) 1.45 g. at 103/O.5 mm and (4) 5.35g. at 88/O.4 mm (distillation on a very short path at non-equilibriumconditions). Isolation of the two products was accomplished bypreparative vapor-liquid chromatography on a 10% W 98 on chromosorb W (MW) column at a flow rate of 85cc/min. The detector, injection port andexit port were 250, 250 and 250C. respectively. Injection was performedon column. The

column temperature was programmed at 10/min. between 80 and 205. Almosttotal hydrolysis of the trimethyl silylated derivatives occured at theexit port and the original phosphorous alcohols were isolatedindividually in dry ice-acetone cooled traps. The trimethysilanol whichformed as a result of hydrolysis vaporized out during productcollection.

The compounds methyl 2-hydroxyethylmethylphosphinate and methyl2-hydroxyethylmethylolphosphinate were identified by mass spectral data,H NMR, P NMR and infrared spectra.

EXAMPLE 3 303 g. of a colorless viscous liquid produced as in Example l.was introduced into a mechanically stirred 2 liter, three-necked,round-bottom Pyrex flask containing ml. dry methanol equipped withnitrogen purge. After the stirred mixture became one phase 750 g.dioxane was introduced slowly over a period of 30 minutes at 25. Thematerial became turbid and finally separated into two translucentlayers. The upper (dioxane) phase was transparent after standingovernight. Separation of the upper phase followed by removal of dioxaneunder partial vacuum below 50 afforded 36.8 g. of residue product(dioxane fraction).

The dioxane fraction was stirred mechanically in a 250 ml.,round-bottom, three necked Pyrex flask equipped with nitrogen purge andreflux-condenser. N,O-bis-trimethylsilylacetamide (45 g.) was added overa period of 15 minutes with stirring. After stirring an additional 120minutes the mixture was one phase.

Vacuum fractional distillation afforded, in addition to acetamide andN,O-bis-trimethylacetamide, four product cuts: (1) 12.91 g. at 56/0.70mm, (2) 32.1 g. at 68/0.17 mm, (3) 4.48 g. at l03/0.5v mm and (4) 16.19g. at 88/0.4 mm (distillation on a very short path at non-equilibriumconditions). lsolation of the two products was accomplished bypreparative vapor-liquid chromatography on a 10% w 98 on chromosorb W (MW) column at a flow rate of 85cc/min. The detector, injection port andexit port were 250, 250 and 250C. respectively. Injection was performedon column. The column temperature was programmed at 10/min. between and205. Almost total hydrolysis of the trimethyl silylated derivativesoccurred at the exit port and the original phosphorous alcohols wereisolated individually in dry ice-acetone cooled traps. Thetrimethylsilanol which formed as a result of hydrolysis vaporized outduring product collection.

The compounds Methyl 2-hydroxyethylmethylphosphinate and methyl2-hydroxyethylmethylolphosphinate were identified by mass spectral data,l-l NMR, P NMR and infrared spectra.

Although certain preferred embodiments of the invention have beendisclosed for purposes of illustration, it will be evident that variouschanges and modifications may be made therein without departing from thescope and spirit of the invention.

lclaim:

1. Compounds of the formula:

wherein R is methyl or hydroxymethyl.

. Methyl Z-hydroxyethylmethylphosphinate.

. Methyl 2-hydroxyethylmethylolphosphinate.

. Process which comprises the steps of reacting elemental phosphorus,methanol and ethylene oxide at a temperature of about 25C. to about200C. in the presence of N,N- dimethylethanolamine to produce an organophosphorus composition, and thereafter reacting saidorganophosphorus composition with formaldehyde in order to convertsubstantially all of the phosphinous hydrogen to hydroxymethyl;

. admixing the product from step (a) with a solvent selected from thegroup consisting of methanol, ethanol and ethylene glycol, in an amountwithin the range of 5 to 30 parts per hundred parts of phosphorusreaction product by weight;

adding a solvent selected from the group consisting of diethyl ether,dioxane, glyme, and diglyme to said admixture accompanied withagitation, the amount of solvent of step being 7 to 15 parts by weightbased on the weight of the solvent of step separating a solvent fractionfrom step (c) above; adding to said solvent fraction from step ((1)above a compound selected from the group consisting of wherein R ismethyl or hydroxymethyl.

5. Process according to claim 4 wherein the compound recovered from step(f) is methyl 2-hydroxymethylphosphinate.

6. Process according to claim 4 wherein the compound recovered from step(f) is methyl 2-,hydroxyethylmethylolphosphinate 7. Process according toclaim 4 wherein the solvent of step (b) is methanol.

8. Process according to claim 4 wherein the compound of step (e) isN,O-bis-trimethylsilylacetamide.

2. Methyl 2-hydroxyethylmethylphosphinate.
 3. Methyl2-hydroxyethylmethylolphosphinate.
 4. Process which comprises the stepsof a. reacting elemental phosphorus, methanol and ethylene oxide at atemperature of about 25*C. to about 200*C. in the presence ofN,N-dimethylethanolamine to produce an organophosphorus composition, andthereafter reacting said organophosphorus composition with formaldehydein order to convert substantially all of the phosphinous hydrogen tohydroxymethyl; b. admixing the product from step (a) with a solventselected from the group consisting of methanol, ethanol and ethyleneglycol, in an amount within the range of 5 to 30 parts per hundred partsof phosphorus reaction product by weight; c. adding a solvent selectedfrom the group consisting of diethyl ether, dioxane, glyme, and diglymeto said admixture accompanied with agitation, the amount of solvent ofstep (c) being 7 to 15 parts by weight based on the weight of thesolvent of step (b); d. separating a solvent fraction from step (c)above; e. adding to said solvent fraction from step (d) above a compoundselected from the group consisting of N,O-bis-trimethylsilylacetamide,trimethylsilylimidazole and N,O-bis-trimethylsilyltrifluoroacetamide, toform methyl 2-trimethylsiloxyethylmethylphosphinate and methyl2-trimethylsiloxyethyltrimethylsiloxymethylphosphinate and thereafter f.hydrolyzing and recovering compounds of the formula wherein R is methylor hydroxymethyl.
 5. Process according to claim 4 wherein the compoundrecovered from step (f) is methyl 2-hydroxymethylphosphinate.
 6. Processaccording to claim 4 wherein the compound recovered from step (f) ismethyl 2-hydroxyethylmethylolphosphinate.
 7. Process according to claim4 wherein the solvent of step (b) is methanol.
 8. Process according toclaim 4 wherein the compound of step (e) isN,O-bis-triMethylsilylacetamide.